Such installations are well known to those skilled in the art, as shown in particular by the patent EP 0 440 477.
In such installations, the cup is provided, at its bottom, with an injection opening adapted to the valve of an aerosol receptacle pre-filled with propulsive gas to permit, with the help of a jack of a piston, the transfer of the contents of the cup, such as paint, into the aerosol receptacle. Once this latter is filled with the liquid product to be received, the diffuser is placed on the valve of the receptacle. The actuation of the diffuser permits rejection of the liquid contained in the receptacle.
Installations permitting such a filling always define a chamber closed at least partially by a door, this door being necessarily maintained closed for reasons of safety during operation of transfer of the liquid corresponding to the movement of the piston in the direction of the bottom of the cup. In the course of this transfer, the piston applies a pressure force to the surface of the liquid contained in the cup. Up till now, the safety device, for holding the door in closed position during the transfer operation, has been constituted by a contactor positioned on the frame, the closing. of the door giving rise to actuation of the contactor and correspondingly to the possibility for the piston to operate. The contactor thus serves only to stop the movement of the piston in case of opening the door. It does not permit in any case controlling a movement of the piston. To permit a movement of the piston, the frame comprises a control member, such as a pushbutton, whose actuation gives rise to the insertion or withdrawal of the piston.
This combination of a contactor and a control member of the piston, such as a pushbutton, has a certain number of drawbacks.
It is first of all relatively easy to shunt the contactor by applying any element against the contactor such that the latter detects continuously a closed position of the door. In this case, the safety of the operations is not ensured.
Another drawback resides in the fact that two operations are necessary to permit the operation of the piston, namely, on the one hand, closing the door so as to actuate the contactor, on the other, acting on the control member for displacement of the piston, such as a pushbutton. These operations are seen to be difficult for the operator. Moreover, the opening of the door automatically triggers the rise of the piston, prohibiting the stopping of the piston in a withdrawn position, which requires cleaning the piston in a high position. To be able to clean the piston when the latter is in a low position, the users have to frustrate the contactor that closes the door.